Apparatus for testing the vane anchorage of turbine vanes

ABSTRACT

Testing apparatus for determining tightness, deformations and weak points of the vane anchorage of a turbine vane. The apparatus operates by applying forces to a vane, which includes a vane base, attached in the normal fashion to a simulated portion of a turbine rotor. A force in a direction corresponding to the radial direction in a turbine rotor and hence to the direction of centrifugal force in a rotating rotor is applied by attaching the vane and rotor portion to respective first and second yokes separated by resilient elements and drawing the vane and rotor portions apart. A force in a direction corresponding to the axial and/or tangential directions of a turbine rotor and hence the direction of the forces of the driving fluid which act on the vanes during operation of a turbine is applied by an additional device while the vane and rotor portions are held in the yokes.

United States Patent [72] Inventors Klaus Detert;

Hans-Jochen Lipp;.Erich Winschuh, all of Neu-lsenburg, Germany [211App]. No. 827,537 [22] Filed June 26, 1969 {45] Patented Sept. 7, 1971[73] Assignee Licentia Patent-Verwaltungs G.m.b.H.

Frankfurt, Germany [32] Priority May 25, 1968 [33] Germany [31] P 17 73500.1

[54] APPARATUS FOR TESTING THE VANE ANCHORAGE 0F TURBINE VANES 6 Claims,4 Drawing Figs.

[52] US. Cl 73/95, 73/92, 73/100 [51] Int. Cl G0ln 3/08, G0ln 3/28, G0ln3/24 [50] Field of Search 73/464, 71.1, 95, 67, 100, 93, 90, 91, 92,101, 102, 97

[56] References Cited UNITED STATES PATENTS 1,409,842 3/1922 Foster73/91 1,485,835 3/1924 Bothezat 73/91 2,007,286 7/1935 Schopper 73/912,469,346 5 /1949 Watter 173/1 90 ABSTRACT:

Kennedy et al., Creep & Fatigue, Journal of Scientific Instruments Vol.33, Nov. 1956 pp. 409- 410.

Fatigue Testing, Weibull 1961 TA- 413- W4 pp. 32, 33, 50, 51

Primary ExaminerRichard C. Queisser Assistant Examiner-John WhalenAtt0rneySpencer & Kaye Testing apparatus for determining tightness,deformations and weak points of the vane anchorage of a tur' bine vane.The apparatus operates by applying forces to a vane, which includes avane base, attached in the normal fashion to a simulated portion of aturbine rotor. A force in a direction corresponding to the radialdirection in a turbine rotor and hence to the direction of centrifugalforce in a rotating rotor is applied by attaching the vane and rotorportion to respective first and second yokes separated by resilientelements and drawing the vane and rotor portions apart. A force in adirection corresponding to the axial and/or tangential directions of aturbine rotor and hence the direction of the forces of the driving fluidwhich act on the vanes during operation of a turbine is applied by anadditional device while the vane and rotor portions are held in theyokes.

1 a i l PATENTEDSEP TISYI 3.603.143 sum 20F 2 v lnyantors;

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Hans-Jocizan PP Ericl \o'mscizul 35: 2 ww 2 w Rttornegs APPARATUS FORTESTING THE VANE ANCHORAGE OF TURBINE VANES BACKGROUND OF THE INVENTIONThe present invention relates to a testing device for determiningtightness, deformations (warping) and weak points of the vane anchorageof turbine vanes.

When constructing large turbines, such as steam turbines, it isnecessary to design the turbine vanes or blades so that when attached oranchored to the turbine rotor and placed under the stresses of operationthey will not be subject to failure, e.g., by cracking at their basewhere the greatest stresses appear. In order to avoid this type ofdamage in completed turbines, it is desirable to provide apparatus whichis capable of simulating the various stresses that act on turbine bladesduring normal operation to permit an experimental verification of thestresses determined by theoretical calculation.

SUMMARY OF THE INVENTION An object of the present invention, therefore,is to provide suitable apparatus which simulates the centrifugal andfluid (.e.g., steam) forces which act, in practice, upon the vaneanchorage of turbine vanes. More particularly, it is an object of thepresent invention to provide a device which permits the determination ofthe elastic deformation s in the base of a turbine vane; detection ofany tilting or slippage of a turbine vane; as well as the location ofthe weak points of a turbine vane at which possible permanentdeformations, cracks or breaks may occur through an overstress duringoperation of a turbine. i

This object, as well as other objects which will become apparent in thediscussion that follows is achieved, according to the present invention,by simulating both a portion of a turbine rotor and a turbine vanehaving a vane base attached to the rotor portion: by providing means forapplying a force to the simulated rotor and vane in a directioncorresponding to the radial direction of a rotor and hence to thedirection of centrifugal force which acts in a rotating rotor and byproviding means for applying a force to the vane in at least onedirection transverse to the direction corresponding to that ofcentrifugal force. This second force is thus applied in a directioncorresponding to the axial and/or tangential directions of a rotor andhence to the direction of the forces of the driving fluid which act on avane during operation of the turbine.

According to a preferred embodiment of the present invention thesimulated rotor portion is attached to a first yoke, the vane isattached to a second yoke and the two yokes are supported in aspaced-apart relationship by means of suitable resilient elements. Themeans for applying the force corresponding to the centrifugal force isrealized by a device for attaching the second yoke to the simulatedrotor portion.

According to another preferred embodiment of the present invention, themeans which apply the force to the vane to simulate the force of adriving fluid (e.g., steam) include means for periodically varying thisforce.

According to a further embodiment of the present invention means areprovided to heat the joint between the simulated rotor portion and thevane.

Finally, it is practical if means are provided to detect the relativemotion between the base of the vane and the rotor portion and to measurethe deformations in the joint between the vane and the rotor portion asthe various loading forces are applied. In the preferred embodiment ofthe present invention the motion-detecting device is realized by alight-optical measuring instrument while the deformations can bemeasured by devices such as dial gauges.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a cross-sectional viewthrough a portion of the testing apparatus according to a preferredembodiment of the present invention.

FIG. 2 is an elevational, and partly schematic illustration of apparatusfor simulating the application of the forces of a driving fluid in thetesting apparatus of FIG. 1.

FIG. 3 is an enlarged cross-sectional view of a portion of the apparatusof FIG. 1 showing a joint comprising the straddling base ofa turbinevane and an impeller hub ofa turbine rotor.

FIG. 4 is a schematic illustration of a light-optical measuring devicewhich may be used in the apparatus of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments ofthe present invention will now be described in connection with FIGS. 1-4of the drawing. The testing apparatus illustrated in FIG. 1 comprises anadjustable frame 1 constructed to hold a turbine vane 2 together with arotor segment 3 and a shaft or shank 4. The frame 1 includes two yokes 5and 8 which are mounted on support columns 9 and 10. The turbine vane 2is fastened in the central portion of the frame 1 on the yoke 5 whichhas a U- shaped profile. The yokes 5 and 8 are spaced apart by braces 6and 7 consisting of resilient elements 11 and 13 and supporting sleevesl2 and 14, respectively.

A hydraulic stretching or pulling device 15 is arranged on the yoke 8and provided with a pull rod 16 which has one end attached to the shaft4 of the rotor segment 3. The shaft 4 is guided in a sleeve 17 fastenedto the yoke 8. The shaft 4 is therefore supported by the pulling device15, which, in turn, abuts against the yoke 8.

In order to brace the vane 2 with respect to the rotor segment 3, thetop plate 18 of the vane 2 is welded to a plate 19 that is bolted to theyoke 5.

The yoke 5 is braced with respect to the yoke 8 by the resilientelements 11 and 13. These resilient elements may, for example, consistof laminations of metal and rubber. The purpose of the resilientelements is to allow the yoke 5, and thus the vane 2, sufficient freedomof movement in the horizontal direction; that is, in the directioncorresponding to the tangential and/or axial direction of the assumedrotor.

The pulling device 15, which is supplied with a hydraulic fluid underpressure, operates to apply a static force to the turbine vane anchor:i.e., a force which corresponds to the centrifugal force acting on arotating rotor. The magnitude of this force can be adjusted and measuredby controlling and measuring the hydraulic pressure. In addition, thisvertically acting force can be measured by means of the springdeflection of the resilient elements 11 and 13.

In order to simulate the operating conditions of a turbine, the jointbetween the vane 2 and the rotor segment 3 is preferably heated, by aheating device 50, to the temperatures reached during operation.

FIG. 2 schematically illustrates a preferred embodiment of apparatus,according to the present invention, for applying forces to the vane 2which correspond to the forces of a vanedriving fluid; that is, forexample, the forces applied to the vanes of a turbine by steam. Thisforce-applying apparatus includes a loop 30 of wire rope arranged tosurround the vane blade, a length of wire rope 31, a tension-controllingdevice 32 and a spring 33. By tensioning the wire rope 31 with thedevice 32 a prescribed force can be applied to the turbine blade 2 inthe horizontal direction. Depending upon the position of the blade 2with respect to the yoke 5, the force can be exerted in a directioncorresponding to the axial and/or tangential directions as defined bythe assumed rotor. A force in the axial direction effects a bending inthe maximum direction" and possibly causes the blade to tilt. A forceapplied in the tangential direction effects a bending in the minimumdirection" and possibly causes the vane 2 to slide on the rotor segment3.

wire rope 34 can therefore be moved back and forth at a frequency, forexample, of 3 Hz. Since the forces of a driving fluid such as steamresult in impulses on turbine vanes in the axial direction, first in thedirection of the emerging steam and then in the opposite direction, thevane 2 can also be tensioned in the identical manner in the oppositedirection by the wire rope 31.

The movement of the base of the vane with respect to the rotor segment 3during the application, to the vane 2, of the horizontal loading forcesis measured by viewing the change in the angular position between twosuitable external surfaces on the rotor segment and the base of thevane. This angular change is determined by a light-optical device whichemploys mirrors 40 and 41 arranged on the external surfaces of theelements 2 and 3 as shown in FIG. 3.

,FIG. 4 schematically illustrates the construction of this lightopticalmeasuring device. In addition to the mirrors40 and 41, the device isprovided with a light source 42 and a measuring'screen 43 having asuitable scale. The mirrors 40 and 41 reflect a light beam from thelight source 42 to the screen 43. The forces acting on the vane2 producesmall movements within the vane anchorage which result in a displacementof the light marks on the screen 43. A properly rigid coupling betweenthe base of the vane and the rotor seginent leads to identical movementsin the reflected light beams. A relative motion between the vane baseand the rotor segment results in a change in the distance between thelight marks on the screen. If the relative movements remain within theelastic limits of the vane and rotor, this change will be small.However, if the vane 2 tilts or slides with respect to the rotor segment3, there will be a considerable change in the distance between themarks.

During operation of a turbine a centrifugal force acts on the turbinevanes causing the supporting shoulders at the base of the vanes to pressagainst the corresponding shoulders of the rotor segment. This conditionmay be simulated by the apparatus according to the present invention totest the quality of the vane anchorage.

When a centrifugal force or simulated centrifugal force is appliedbetween vane and rotor (the latter by the pulling device elasticdeformations occur in the base ofthe vane and in the rotor segment, asshown in FIG. 3, causing an increase in the distance it between theupper surface of the rotor segment and the lower surface of the mainbody of the vane. This change in the distance it can be measured, independence upon the applied force Z, by suitable measuring elements suchas dial gauges. This distance change should be measured both at thebelly and at the backside of the vane to detect any settling as well asany increases in distance caused by an elastic elongation of the vane.

Measuring elements such as dial gauges 51 can also be applied at thepoints 24 in the middle of the vane 2 to measure the spread at the baseof the vane in relation to the applied force Z. This measurement makesit possible to determine when one or both of the sides of the vane basecome in contact with the retaining catches of the rotor segment 3. Byremoval of the retaining catches it is also possible to determine thespread at the base of the vane for all vaiues of applied force.

The principal component of the forces applied by the driving fluid(e.g., steam) acts in the circumferential direction of the assumedrotor. By tensioning the wire rope in this direction, it is possible,with the apparatus according to the.

present invention to determine that tangential force which causes thevane to slide, given various values of the pulling force 2. Use of theoptical measuring device illustrated in FIG.

4 to detect a change in the relative positions of the sides of the baseof the vane and the intersecting plane of the rotor segment, make itpossible to determine elastic flexure at the base of the vane independence upon the force applied in the tangential direction. 3

The vane-driving fluid also exerts forces, or rather force impulses, ona vane in the axial direction of the assumed rotor.

By rotating the yanc on its mountb the wire rope can be employed tosimulate these axia ly directed forces to investigate their effects.

In particular, it is possible to investigate the bending ortiltingmovements of the vane which are executed at the vane base. lf thetension of the wire rope is varied, it is possible to determine theangular variations in the position of the external surfaces of the vanebase and the rotor segment in dependence upon the pulling force Z.Information concerning the seating I tions and weak points of the vaneanchorage of turbine vanes 7 comprising, in combination:

a. means simulating a portion of a turbine rotor;

b. vane means, comprising at least a portion of a turbine vane and avane base, attached to said rotor portion;

c. a first yoke;

d. a second yoke connected to said first yoke;

e. resilient element means for resiliently supporting said first yokewith respect to said second yoke, said first and second yokes and saidresilient means forming a frame for supporting said vane means;

f. first means for attaching said first yoke to said vane means;

g. second means for attaching said second yoke to said simulated rotorportion, said second means including means-for applying a force to saidsimulated rotor portion corresponding to the radial direction of a rotorand hence to the direction of the centrifugal force in a rotating rotor;and

h. means for applying a force directly to said vane means in at leastone direction transverse to the force applied by said second attachingmeans corresponding to the axial and/or tangential directions of a rotorand hence to the direction of the forces of a driving fluid which act ona vane during operation of a turbine.

2. The apparatus defined in claim 1, wherein said means for applying aforce to said vane means in said transverse direction includes means forperiodically varying the force.

3. The apparatus defined in claim 2, further comprising means forheating the joint between said simulated rotor portion and said vanemeans.

4. The apparatus defined in claim 3, further comprising light-opticalmeasuring means for measuring relative motion between said vane base andsaid simulated rotor portion during the application of forces to saidvane means and said simulated rotor portion.

5. The apparatus defined in claim 4, further comprising measuring meansfor measuring deformations in said vane means and said simulated rotorportion during the application of forces to said vane means and saidsimulated rotor portion.

6. The apparatus defined in claim 1, wherein said radial force applyingmeans is a hydraulic device.

UNITED STATES PATENT OFFHIE CERTFFICATE GF CORRECTKON Patent No. 3 603,143 Dated September 7th. 1971 Invent0r(s)Klaus Detert, Hans-Jochen Limaand Erich Winschuh It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

i In the heading of the patent, line 5, change "June 26, 1969" to --May26, l969-.

Signed and sealed this 23rd day of May 1972.

(SEAL) A"l st:

EDWARD PLFLETCITERJR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents JFxM PO-1050 (10-69) uscoMM-oc suave-Pen U 5, GOVERNMENTPRKNTING OFFLCE I989 0-3ti-331

1. Testing apparatus for determining tightness, deformations and weakpoints of the vane anchorage of turbine vanes comprising, incombination: a. means simulating a portion of a turbine rotor; b. vanemeans, comprising at least a portion of a turbine vane and a vane base,attached to said rotor portion; c. a first yoke; d. a second yokeconnected to said first yoke; e. resilient element means for resilientlysupporting said first yoke with respect to said second yoke, said firstand second yokes and said resilient means forming a frame for supportingsaid vane means; f. first means for attaching said first yoke to saidvane means; g. second means for attaching said second yoke to saidsimulated rotor portion, said second means including means for applyinga force to said simulated rotor portion corresponding to the radialdirection of a rotor and hence to the direction of the centrifugal forcein a rotating rotor; and h. means for applying a force directly to saidvane means in at least one direction transverse to tHe force applied bysaid second attaching means corresponding to the axial and/or tangentialdirections of a rotor and hence to the direction of the forces of adriving fluid which act on a vane during operation of a turbine.
 2. Theapparatus defined in claim 1, wherein said means for applying a force tosaid vane means in said transverse direction includes means forperiodically varying the force.
 3. The apparatus defined in claim 2,further comprising means for heating the joint between said simulatedrotor portion and said vane means.
 4. The apparatus defined in claim 3,further comprising light-optical measuring means for measuring relativemotion between said vane base and said simulated rotor portion duringthe application of forces to said vane means and said simulated rotorportion.
 5. The apparatus defined in claim 4, further comprisingmeasuring means for measuring deformations in said vane means and saidsimulated rotor portion during the application of forces to said vanemeans and said simulated rotor portion.
 6. The apparatus defined inclaim 1, wherein said radial force applying means is a hydraulic device.